Chair

ABSTRACT

A chair structure results in a proper counter force when an occupant reclines on a back. The chair is composed of a pintle, a base which is supported by the pintle, a back support which is installed on the back, a seat support which is installed on a seat, a first swaying pivot, a second swaying pivot which is located in front of the first swaying pivot, a third swaying pivot which is located between the first swaying pivot and the second swaying pivot, and a sliding structure. The chair is provided with simple structures, and can result in a constant counter force or maintain a proper counter force depending on an angle of the back, when the occupant reclines on the back.

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to a chair, and more particularly to a chair which is linked to rearward tilt of a chair back, allowing a chair seat to be raised.

b) Description of the Prior Art

In spite that a chair which is linked to rearward tilt of a chair back for lowering a chair seat is more and more popular, in terms of a chair which is linked to sway of the chair back and allows a chair seat to be displaced synchronously, on the contrary, there is also a chair which is linked to the rearward tilt of the chair back for raising the chair seat.

For the chair that is linked to the rearward tilt of the chair back for raising the chair seat, there is an ergonomic chair structure disclosed in an international patent publication No. WO 00/74531. As shown in FIG. 36 and FIG. 37, the chair includes the pintle 101, the base 102 that is supported by the pintle 101, the back support 104 that is installed on the back 103, the seat support 106 that is installed on the seat 105, the horizontal pivot point 107 that is connected on the base 102 to tilt the back support 104 rearwards, the support arm 108 that is located on the base 102 to connect the seat support 106, and the horizontal pivot point 109 that connects the back support extension 112 of the back support 104 to the seat support 106. After the back 103, which was put upright as shown in FIG. 36, is tilted rearwards as shown in FIG. 37, the horizontal pivot point 109 will be raised. Besides, through the rising of the horizontal pivot point 109, the support arm 108, which was tilted forwards, can be raised. As a result, the linkage is generated with the rearward tilt of the back 103, thereby allowing the seat 105 to be raised.

In this chair, the force that lowers the seat 105 becomes the force for putting the back 103 upright. As a result, the weight of the occupant who sits on the seat 105 will result in the resistance against the rearward tilt of the back 103. Therefore, the heavier the occupant is, the larger the force will be needed to tilt the back 103 rearwards for resulting in the counter force, which is formed when the back 103 is tilted rearwards, to be fitted with the weight of the occupant.

However, there indeed exists following issues and shortcomings required to be improved, upon using the aforementioned chair.

For the conventional chair, when the seat 105 is raised, the support arm 108 will rotate at the center through the horizontal pivot point 110 at the underside, to change from the forward tilt condition to the upright condition, as shown by a curve C in FIG. 27, which is a stage that the support arm 108 starts to be putted upright. In other words, at the stage that the back starts to be tilted rearwards, the seat 105 will be changed into the maximum liftable condition. As shown by the curve C in FIG. 27, in the process that the occupant tilts the back 103 rearwards, the counter force at the initial stage of the process will be the largest, and is then decreased. For this kind of chair, a larger force is required when the back 103 starts to be tilted; whereas, the occupant should recline hard on the back 103. Nevertheless, when the back 103 is tilted to a certain extent, the counter force will be weakened suddenly, allowing the back 103 to be easily tilted abruptly. As a result, the counter force is not configured appropriately.

On the other hand, as this kind of chair uses the support arm 108 which connects the front half of the seat support 106 with the base 102, more parts are required correspondingly. In other words, the support arm 108 will become the necessary accessory, and the horizontal pivot points 110, 111 should be also installed on the support arm 108. Therefore, the parts will be increased, manufacturing cost will be increased and a more complex structure will be induced.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a chair which includes a pintle; a base which is supported by the aforementioned pintle; a back support which is installed on a back; a seat support which is installed on a seat; a first swaying pivot which is located on the aforementioned base to connect with the aforementioned back support; a second swaying pivot, which is located in front of the aforementioned first swaying pivot, is at a same level as that of the first swaying pivot, is displaced upwards or above the first swaying pivot, and connects the aforementioned seat support on the base in an upward or downward sway manner; a third swaying pivot, which is located between the first swaying pivot and the second swaying pivot, is displaced at a location higher than a connecting line that connects the first swaying pivot and the second swaying pivot, such that the aforementioned back is support and the seat support can be connected to sway upwards and downwards, and that the third swaying pivot can be linked with rearward tilt of the back support to raise; and a sliding structure, which is linked with rising of the aforementioned third swaying pivot, allowing the second swaying pivot to be guided along a rear upper slant direction.

Accordingly, when the back and the back support are tilted rearwards with the first swaying pivot as a center, a rear side is swayed immediately. Therefore, the third swaying pivot will be raised, and the second swaying pivot will be displaced along the rear upper slant direction, in association with the rising of the third swaying pivot. As a result, the seat support, which is supported by the second swaying pivot and the third swaying pivot, will be raised entirely. Accordingly, weight of an occupant that operates along a direction for lowering the seat support will result in a counter force against the rearward tilt of the back. Under this condition, the second swaying pivot will be guided to move along the rear upper slant direction by a function of the sliding structure. Hence, in a stage that the rearward tilt starts, the seat support will not be raised significantly and then slightly, and in an initial stage that the back is tilted rearwards, the rising of the seat support will not be enhanced quickly, thereby preventing from a condition that an extremely large counter force occurs suddenly and then diminishes, at the initial stage that the back is titled rearwards.

Another object of the present invention is that in a chair of the present invention, the sliding structure will guide the second swaying pivot along a straight line, or to be protruded out of a circular arc at an underside. As a result, when the back starts to be tilted rearwards, from the initial stage to a final stage that the back is tilted rearwards; a rising rate of the second swaying pivot will be equalized, and gradually increased following the rearward tilt of the back. At this time, if a rearward tilt angle of the back is increased by θ, and a rising distance of the second swaying pivot is assumed to be h, then the rising rate of the second swaying pivot will be h/θ. Therefore, the rising of the seat will be equalized as shown by a curve A, or be gradually increased as shown by a curve B, upon tilting the back rearwards. Accordingly, the counter force will be equalized as shown by the curve A, or be gradually increased as shown by the curve B.

Still another object of the present invention is to provide a locking structure on the base for fixing the back support. As a result, the back support can be prevented from being tilted rearwards by an operation of the locking structure, and after the operation of the locking structure has been released, the back support can be restored to a condition that it can be tilted rearwards.

Yet still another object of the present invention is to provide a locking structure which is provided with a swaying unit to fix the back support, a support arm to sway the swaying unit, and an operating structure to displace the support arm, such that under a condition that sway of the swaying unit, which is located on the support arm, is restricted, and when the operating structure is operated, an elastic deformation is formed to absorb a displacement of the swaying unit for accumulating energy, thereby swaying the swaying unit.

Accordingly, by the operation of the operating structure, the support arm will sway the swaying unit to fix the back support or to release the fixing state. In other words, after the locking structure has started to operate, the rearward tilt of the back support will be prohibited; or the back support can be tilted rearwards as the operation of the locking structure is released. When the back support is titling rearwards, the sway of the swaying unit is restricted due to the back support. Under this condition, through controlling the operating structure, an elastic deformation part which is disposed on the support arm will be deformed elastically to absorb the displacement of the swaying unit for accumulating energy, without swaying the swaying unit reluctantly. Besides, once the back support, which was titled rearwards originally, is putted upright, the swaying unit can sway. Therefore, under a condition that the elastic deformation part is restored to its original shape after being deformed elastically, the swaying unit will sway.

To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a first embodiment of a chair of the present invention, wherein a back is not tilted rearwards.

FIG. 2 shows a side view of a chair of the present invention, wherein a back is tilted rearwards.

FIG. 3 shows cutaway views of a base, a back support, and a seat support of a chair of the present invention, with (A) being a state that the back support is not tilted rearwards, and (B) being a state that the back support is titled rearwards.

FIG. 4 shows a plan view of a back support that is assembled to a base.

FIG. 5 shows a cutaway view along a line V-V of FIG. 3, for describing a height adjustment structure.

FIG. 6 shows a cutaway view of an enlarged installation part of an operating rod of a height adjustment structure.

FIG. 7 shows a side view of a second embodiment of a chair of the present invention.

FIG. 8 shows cutaway view of a locking structure of a chair of the present invention, with (A) being a state that a back support is not fixed, and (B) being a state that the back support is fixed.

FIG. 9 shows a plan view of a locking structure of a chair of the present invention.

FIG. 10 shows a turn-over unit of a locking structure of a chair of the present invention, with (A) being a front view of a state that a back support is not fixed, and (B) being a front view of a state that a back support is fixed.

FIG. 11 shows a cutaway view of a swaying unit of a locking structure of a chair of the present invention, wherein the swaying unit is installed on a base.

FIG. 12 shows a front view of a seat installation part which is fixed on a back support.

FIG. 13 shows a front view of an armrest installation part which is fixed on a seat support.

FIG. 14 shows a side view of an embodiment, excluding a sliding structure.

FIG. 15 shows a side view of an embodiment, excluding a counter force structure.

FIG. 16 shows a side view of a counter force structure and another embodiment.

FIG. 17 shows a bottom view of a first type of a representative installation structure of a seat.

FIG. 18 shows a cutaway view along a line A-A of FIG. 17.

FIG. 19 shows a cutaway view along a line B-B of FIG. 17.

FIG. 20 shows a bottom view of a second type of a representative installation structure of a seat.

FIG. 21 shows a cutaway view along a line A-A of FIG. 20.

FIG. 22 shows a bottom view of a third type of a representative installation structure of a seat.

FIG. 23 shows a side view of an installation structure of FIG. 22.

FIG. 24 shows a front view of an installation structure of FIG. 22.

FIG. 25 shows a top view of a fourth type of a representative installation structure of a seat.

FIG. 26 shows a cutaway view along a line A-A of FIG. 25.

FIG. 27 shows a graph of variations between a rearward tilt angle of a back and a seat height of the prior art.

FIG. 28 shows a graph of variations between a rearward tilt angle of a back and a resulted counter force.

FIG. 29 shows a cutaway view of another embodiment of an installation structure of an operating rod of a height adjustment structure.

FIG. 30 shows a cutaway view of a locking structure and another embodiment wherein a back support is not fixed.

FIG. 31 shows a cutaway view of a locking structure wherein a back support is fixed.

FIG. 32 shows a plan view of a locking structure.

FIG. 33 shows a cutaway view along a line X-X of FIG. 32.

FIG. 34 shows a cutaway view along a line Y-Y of FIG. 33.

FIG. 35 shows a cutaway view along a line Z-Z of FIG. 33.

FIG. 36 shows a side view of a conventional chair of the prior art, wherein a back is not tilted rearwards.

FIG. 37 shows a side view of a chair of the prior art, wherein a back is tilted rearwards.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 6, showing a first embodiment of a chair of the present invention, a chair is provided with a pintle 1; a base 2, which is supported by the pintle 1; a back support 4, which is installed on a back 3; a seat support 6, which is installed on a seat 5; a first swaying pivot 7, which is connected at the base 2 to tilt the back support 4 rearwards; a second swaying pivot 8, which is connected at the base 2 to sway the seat support 6 upwards and downwards; a third swaying pivot 9, which connects the back support 4 and the seat support 6 to sway the back support 4 and the seat support 6 upwards and downwards, and which is linked to rearward tilt of the back support 4, such that the third swaying pivot 9 can be raised along with the back support 4; and a sliding structure 10, which is linked to rising of the third swaying pivot 9 to guide the second swaying pivot 8 along a rear upper slant direction.

The base 2 is latched on a top of the pintle 1, and a bottom plate 2 a of the base 2 is provided with a cylinder 2 b, a diameter of which is gradually reduced from bottom to top. In addition, an interior of the pintle 1 is provided with a pneumatic spring 18 to adjust height, a top of this pneumatic spring 18 is protruded out of an upper end of the pintle 1, and a circumference at an upper part of the pneumatic spring 18 is a slant surface with a diameter being gradually reduced from bottom to top. As a result, the base 2 can be installed on the top of the pintle 1 by inserting the upper part of the pneumatic spring 18 into the cylinder 2 b from top to bottom. Rear half parts of left and right side plates 2 c, 2 b of the base 2 are provided with through-holes for transfixing with the first swaying pivot 7, and front half parts are provided with through-holes for transfixing with the second swaying pivot 8. In this embodiment, the through-hole of the second swaying pivot 8 is a long hole to serve as the sliding structure 10. In addition, the long hole will be described as the sliding structure 10, hereafter.

As the seat support 6 supports the seat 5, it can freely sway and be freely installed slidingly on the base 2. The seat support 6 is constituted by an upper plate 6 a above the base 2, and a pair of left and right side plates 6 b, 6 c that are hung down from two side edges of the upper plate 6 a. These parts are formed by bending a piece of board material. In terms of the seat 5, the seat 5 is installed on the upper plate 6 a by screws. In addition, the left and right side plates 6 b, 6 c are disposed at exterior sides of the side plates 2 c, 2 d of the base 2, and central positions of the left and right side plates 6 b, 6 c of the seat support 6 are provided with through-holes for transfixing with the third swaying pivot 9, whereas front half parts are provided with through-holes for transfixing with the second swaying pivot 8.

The back support 4 is to support the back 3, and hence, the back support 4 can be installed on the base 2 in a manner that it can sway freely. The back support 4 is constituted by the side plates 2 c, 2 d of the base 2, a pair of left and right side plates 4 a, 4 b between the side plates 6 b, 6 c of the seat support 6, and a support plate 4 c between the left and right side plates 4 a, 4 b. A front half and a rear half of the support plate 4 c are formed with an elevation difference, with the front half being higher, and the rear half lower. The rear half of the support plate 4 c is loaded with loadings 4 d at the rear halves of the left and right side plates 4 a, 4 b, and the loadings 4 d are fixed by welding or like. By this configuration, the loadings 4 d will be integrally formed with the left and right side plates 4 a, 4 b, as well as the support plate 4 c. By welding or like, an installation plate 11 which is fixed on the back 3 is fixed on the rear half of the support plate 4 c by bolts or like. The front half of the support plate 4 c is extended to a level higher than that of the rear half, and is disposed above the base 2. Central positions of the left and right side plates 4 a, 4 b of the back support 4 are provided with through-holes for transfixing with the first swaying pivot 7, and the front halves are provided with through-holes for transfixing with the third swaying pivot 9.

The first swaying pivot 7 is transfixed into the through-holes of the base 2, and the through-holes located at the back support 4, to connect the back support 4 at the base 2, and to allow the back support 4 to be tilted rearwards. A front end of the first swaying pivot 7 is latched with a pull preventer 12. The second swaying pivot 8 is transfixed into the sliding structures 10 of the base 2, and the through-holes located at the seat support 6, to connect the base 2, such that the seat support 6 can sway upwards and downwards. A front end of the second swaying pivot 8 is latched with the pull preventer 12. The third swaying pivot 9 is transfixed into the through-holes of the seat support 6, and the through-holes located at the back support 4, to connect the seat support 6 with the back support 4, allowing the seat support 6 and the back support 4 to sway. A front end of the third swaying pivot 9 is latched with the pull preventer 12.

The sliding structure 10, such as the long through-hole extended linearly along the rear upper slant direction, is latched with push buttons 13 made by polyacetal at its peripherals, allowing the second swaying pivot 8 to smoothly slide. An angle of the sliding structure 10 is preferably toward the rear upper slant direction, for example, tilting by about 40°-70°, with the best configuration being tilting along the rear upper slant direction at about 55°. Moreover, the length of the sliding structure 10 will be 25 mm under the condition that it is tilted along the rear upper slant direction at 55°, and the second swaying pivot 8, for example, will be raised by about 20 mm.

The second swaying pivot 8 is disposed in front of the first swaying pivot 7, and is at a level higher than that of the first swaying pivot 7. The second swaying pivot 8, following the displacement of the third swaying pivot 9, is guided and displaced to the sliding structure 10, with its range of displacement being in front of the first swaying pivot 7 and above the first swaying pivot 7. However, if the second swaying pivot 8 is disposed in front of the first swaying pivot 7, and is at a same level as that of the first swaying pivot 7, then it can be also guided from this position to the sliding structure 10 along the rear upper slant direction. Besides, even under this condition, the second swaying pivot 8 will be displaced in front of the first swaying pivot 7. Moreover, the third swaying pivot 9 is disposed between the first swaying pivot 7 and the second swaying pivot 8, and is located above a connecting line L that connects the first swaying pivot 7 and the second swaying pivot 8. The third swaying pivot 9 will be displaced following with rearward tilt of the back support 4, with its range of displacement being located between the first swaying pivot 7 and the second swaying pivot 8, and above the connecting line L that connects the first swaying pivot 7 and the second swaying pivot 8.

On the other hand, when the second swaying pivot 8 is at the range below the first swaying pivot 7, no displacement will occur. As a result, the second swaying pivot 8 can be smoothly raised along with the rearward tilt of the back support 4. Assuming that the second swaying pivot 8 is disposed below the first swaying pivot 7, when the third swaying pivot 9 is above the connecting line L that connects the first swaying pivot 7 and the second swaying pivot 8, and is below the first swaying pivot 7, the third swaying pivot 9 will sway toward the rear upper slant direction with the first swaying pivot 7 as an axis, following with the rearward tilt of the back support 4. Therefore, a force of forward operation will be developed on the second swaying pivot 8, prohibiting the second swaying pivot 8 from sliding toward the rear upper slant direction, and allowing the range of displacement of the second swaying pivot 8 to be above the first swaying pivot 7 or at the same level as that of the first swaying pivot 7, so as to avoid the aforementioned condition and to enable the second swaying pivot 8 to be smoothly raised following with the rearward tilt of the back support 4.

A counter force structure 14 is disposed between the base 2 and the back support 4. By exerting a force on a top of the back support 4, the counter force structure 14 will press the back support 4 to restore to an original position when the back support 4 is tilted rearwards. Referring to FIG. 3, the counter force structure 14 is constituted by a coil spring 15 and spring plates 16 at two ends of the coil spring 15. The spring plate 16 at an upper side is folded and latched into a periphery of an axis 17 in the spring plate 16 at a lower side, and a distance between the upper side spring plate 16 and the lower side spring plate 16 will be changed following an extension or compression of the coil spring 15. The lower side spring plate 16 is provided with a concaved part 16 a, and the upper side spring plate 16 is provided with a convex part 16 b. By latching the concaved part 16 a into a convex part 2 g of the base 2, and inserting the convex part 16 b into a concaved part 4 g on the back support 4, the counter force structure 14 can be installed between the base 2 and the back support 4. The counter force structure 14 is disposed at a rear side of the first swaying pivot 7, and once the back support 4 is tilted rearwards, the coil spring 15 will be compressed, thereby resulting in the counter force.

Furthermore, as the pneumatic spring 18, which is used to adjust the height, has been used very commonly, it will not be described further. The pneumatic spring 18 operates through a height adjustment structure 19. The height adjustment structure 19 in this embodiment is composed of an operating rod 20 and an installation tool 21 which is installed at the base 2 to sway the operating rod 20. The operating rod 20 includes an operating stick which is bended into a crank shape, an extension part 20 a which is extended along a breadth direction of the chair for installing an operating plate 22, an shaft branch 20 b which is extended toward a rear side from the extension part 20 a, and an operating part 20 c which is extended toward the breath direction of the chair from a front end of the shaft branch 20 b. The shaft branch 20 b and the operating part 20 c are collected in the base 2, and the extension part 20 a is protruded out of an exterior side of the base 2 from a long through-hole 2 h on the right side plate 2 c of the base 2. By two pieces of relieving arches 2 i disposed at the base 2, and the installation tool 21 of the relieving arch 2 j which is disposed between the relieving arches 2 i, the shaft branch 20 b can be supported and turned over. In other words, concaved locations of the two relieving arches 2 i, and concaved locations of the installation tool 21 will clamp the shaft branch 20 b from top to bottom, so as to constitute a bearing. The operating part 20 c is stuffed into the convex part 18 a of the pneumatic spring 18 to form an operable state. The long through-hole 2 h of the base 2 forms a swaying shape for the operating rod 20. As shown by a solid line in FIG. 5, the operating rod 20 presses down the extension part 20 a by its weight, thereby rising up the operating part 20 c.

Once an occupant has reclined on the back 3, the coil spring 15 of the counter force structure 14 is compressed, and in a mean time, the back 3 and the back support 4 are tilted rearwards with the first swaying pivot 7 as a center. As a result, the third swaying pivot 9 will be raised. In addition, linkage is formed along with the rising of the third swaying pivot 9, allowing the second swaying pivot 8 to be guided to the sliding structure 10 and be displaced along the rear upper slant direction. In other words, as the second swaying pivot 8 and the third swaying pivot 9 are raised, the seat support 6 and the seat 5 are raised too. As the seat is taken by the occupant, and the weight of the occupant becomes a force to restrain the rising of the seat 5, a force that tilts the back 3 rearwards will correspondingly become a counter force.

A chair, a counter force of which as shown by a curve A or a curve B in FIG. 28, can almost have an equalized counter force without a limitation to a rearward tilt angle of the back 3, or can have a counter force which is gradually increased as the rearward tilt angle of the back 3 increases. After the occupant has reclined on the back 3 and tilted the back 3 to a maximum extent, the back 3 will not be easily tilted suddenly, thereby improving comfortableness while being seated. As a result, it is preferably to configure the counter force as that of the curve A or B in FIG. 28.

In the chair of this embodiment, the sliding structure 10 will guide the second swaying pivot 8 toward the rear upper slant direction in a straight line. In addition, the third swaying pivot 9 will be displaced toward the rear upper slant direction along a circumference with the first swaying pivot 7 as a center. Accordingly, a relationship between an increment θ of the rearward tilt angle of the back 3 and a rising distance h of the second swaying pivot 8 will be constant, and from the back 3 starts to be tilted rearwards, to an initial stage and to a final stage of the rearward tilt, all of the rising rates (h/θ) of the second swaying pivot 8 will be equalized. To put it another way, the positions of the first, second, third swaying pivots 7, 8, 9 and the tilt angle of the sliding structure 10 will equalize the rising rates (h/θ) of the second swaying pivot 8 when the back support 4 is tilted rearwards. Therefore, as shown by the curve A in FIG. 27, as the tilt angle of the back support 4 increases, the seat support 6 and the seat 5 will be slowly rising at a certain distance, and the resulted counter force will become a constant. As a result, at a moment when the occupant tilts the back 3 rearwards, there will be no large change to the counter force, and the back 3 can be tilted rearwards continuously with almost the same force. That is to say, for the chair as shown in FIG. 36, the back will be easily tilted due to that the counter force is weakened suddenly, after the back has been tilted to a certain extent; whereas, for the chair of the present invention, this condition can be prevented, thereby improving comfortableness in using the chair.

Referring to FIGS. 1 to 6, in terms of the positions of first, second, third swaying pivots 7, 8, 9, and the tilt angle of the sliding structure 10, when the back support 4 starts to be tilted rearwards, the rising rate (h/θ) of the second swaying pivot 8 will become equalized. In other words, under a condition that the back support 4 is not tilted rearwards, the third swaying pivot 9 is disposed at about 40° in a front upper slant direction of the first swaying pivot 7, and the second swaying pivot 8 is disposed at about 7° in a front upper slant direction of the first swaying pivot 7, if viewing from a side of the chair. Moreover, viewing from the side of the chair, the third swaying pivot 9 is disposed at about 10° in a rear upper slant direction of the second swaying pivot 8. In addition, viewing from the side of the chair, the sliding structure 10 is tilted about 55° toward the rear upper slant direction. Under this condition, once the back support 4 is tilted rearwards, the third swaying pivot 9 will be displaced to a position within about 60° in the front upper slant direction of the first swaying pivot 7, and the second swaying pivot 8 will be displaced to a position within about 15° in the front upper slant direction of the first swaying pivot 7. However, the relationship among the positions of first, second, third swaying pivots 7, 8, 9, and the tilt angle of the sliding structure 10 is not limited to the aforementioned angles, as long as that when the back support 4 is tilted rearwards, the rising rate (h/θ) of the second swaying pivot 8 can be equalized.

On the other hand, once the occupant stops reclining on the back 3 and gets up, the coil spring 15 of the counter force structure 14 will be extended, allowing the back support 4 to be putted up forwards.

This chair is constituted through the sliding structure 10 to guide the third swaying pivot 9, allowing the chair to be composed simply, and thereby controlling an increase of manufacturing cost.

The adjustment of height of the seat 5 is disclosed hereafter. As shown by a solid line in FIG. 5, under a condition that the operating rod 20 is not operated by the occupant, the operating rod 20 will lower down the extension part 20 a by its weight, thereby raising the operating part 20 c. As a result, the convex part 18 a of the pneumatic spring 18 will not operate, its length cannot be changed, the length of the pintle 1 will remain at a constant, and the height of the seat 5 will also remain at a constant.

Once the occupant puts lifts up the operating plate 22 of the operating rod 20, the operating rod 20 will sway with the shaft branch 20 b as a center, as shown by a dotted line in FIG. 5. At this time, the operating part 20 c will be pressed down into the convex part 18 a of the pneumatic spring 18. As a result, the length of the pneumatic spring 18 can be adjusted, and the length of the pintle 1 can be changed to adjust the height of the seat 5. Next, after the occupant has released the operating rod 20, the operating rod 20 will be restored to a non-operating state by its weight.

A second embodiment of the present invention is described hereafter. Besides, in this detailed description and drawings, as a same part is marked by a same numeral, the repeated description will be omitted. Referring to FIGS. 7 to 13, the base 2 is provided with a locking structure 23 to fix the back support 4. The locking structure 23 is provided with a swaying unit 45 to fix the back support 4, a support arm 46 to sway the swaying unit 45, and an operating structure 44 to displace the support arm 46. The operating structure 44, such as a turn-over unit (called the turn-over unit 44 hereafter) is connected to the support arm 46 which sways and displaces the swaying unit 45. However, the operating structure is not limited to the turn-over unit 44, and any structure is acceptable as long as that it enables the support arm 46 to be displaced forwards and rearwards (omitting the drawings). In addition, in this embodiment, an operating plate 47 of the turn-over unit 44 is provided.

The turn-over unit 44 is disposed between the left side plate 2 d and a wall plate 2 n of the base 2, is latched into an axis 48, and cannot be turned over correspondingly. A spring 49 which can press the turn-over unit 44 toward the wall plate 2 n is disposed between the side plate 2 d and the turn-over unit 44. The axis 48 is supported on the side plate 2 d of the base 2, and is protruded outwards from the left side plate 2 d, in a manner that it can turn over freely. The operating plate 47 is installed on the protruded portion of the axis 48.

The turn-over unit 44 is provided with an arm 44 a and a brake 44 b. Referring to FIG. 8(A) and FIG. 10(A), the turn-over unit 44 is turned over from an initial position toward a locking position as shown in FIG. 8(B) and FIG. 10(B). As a result, the turn-over unit 44 will enable the arm 44 a to be folded toward a tilted surface 51 of the wall plate 2 n and to be turned over at a same time. At this time, the tilted surface 51 will be protruded toward the side plate 2 d from an initial position where the arm 44 a is in touch with and a locking position where the arm 44 a is in touch with, so as to press the turn-over unit 44, compress the spring 49, and move toward the side plate 2 d. The arm 44 a is connected to the support arm 46 which can sway. Once the turn-over unit 44 is restored to an original position from the locking position, the brake 44 b will find tune the side plate 2 d to prevent the turn-over unit 44 from excessively turning over.

The swaying unit 45 includes left and right side plates 45 a, 45 b, and a connection plate 45 c that connects the two side plates 45 a, 45 b. The left and right side plates 45 a, 45 b are provided with shafts 45 d, concaved parts 2 p on the base 2 are inserted with the shafts 45 d, a cover plate 52 is enclosed at a top and is fixed on the base 2 by screws 53. The swaying unit 45 is installed on the base 2 in a manner that it can sway with the shafts 45 d as centers. An upper end of the swaying unit 45 is located in front of the shafts 45 d. As a result, when the swaying unit 45 sways at a rear side, the upper end of the swaying unit 45 will be raised and latched into a concaved part 4 h of the back support 4. Under this condition, the upper end of the swaying unit 45 will enter into a range of rearward tilt of the back support 4.

Referring to FIG. 8(A), under a condition that the turn-over unit 44 is restored to the initial position, the support arm 46 will pull up the swaying unit 45 toward a front side, and the upper ends of the side plates 45 a, 45 b will be moved out from the concaved part 4 h of the back support 4. In other words, as the side plates 45 a, 45 b are moved out of the range of rearward tilt of the back support 4, the back support 4 can be tilted rearwards. To put it differently, the back 3 will not be locked.

On the other hand, as shown in FIG. 8(B), once the turn-over unit 44 has been turned over to the locking position, the support arm 46 will allow the swaying unit 45 to sway rearwards. As a result, the upper ends of the side plates 45 a, 45 b will be latched into the concaved part 4 h of the back support 4. In other words, the side plates 45 a, 45 b will enter into the range of rearward tilt of the back support 4, thereby restricting the rearward tilt of the back support 4. To put it another way, the back 3 is locked.

On the other hand, in this embodiment, a support plate 4 c of the back support 4 is divided into a front half 4 ca and a rear half 4 cb. The front half 4 ca is formed by bending a piece of board material, and the rear half 4 cb is integrally formed with the left and right side plates 4 a, 4 b. In other words, the rear half 4 cb and the side plates 4 a, 4 b are formed by bending the board material, and the front half 4 ca is integrally fixed with the left and right side plates 4 a, 4 b by welding or like.

Furthermore, in this embodiment, as shown in FIG. 6 and FIG. 29, the shaft branch 20 b of the operating rod 20 of the height adjustment structure 19 is emplaced in the concaved locations of the two relieving arches 2 i, and at a same time, the location between the relieving arches 2 i is clamped by the plan-shape installation tool 21 from top to bottom, so as to support the operating rod 20 in a manner that the operating rod 20 can be turned over.

Seat installation parts 37, for example, are fixed by welding or like on a top of the seat support 6. The seat installation parts 37 are provided at a front and a rear place. A seat shell 38 is fixed by the seat installation parts 37, and the seat 5 is installed on the seat support 6 with screws, for example. Moreover, on the seat support 6 is provided with armrest installation parts 39 to install the armrests which are fixed by welding or like. Besides, as seen by the chair of this embodiment, the armrests do not need to be installed even there are the armrest installation parts 39.

Even that the chair of this embodiment is the same as that in FIG. 1, when the occupant starts to tilt the back 3 rearwards, there will be no condition that the counter force will be increased in the middle of tilting, and the back 3 can be tilted continuously almost with the same force, thereby increasing comfortableness in using the chair. Moreover, by using the sliding structure 10 to guide the third swaying pivot 9, the chair can be constituted simply, thereby controlling the increase of the manufacturing cost.

On the other hand, the aforementioned embodiment is only one of the proper embodiments of the present invention, and is not the necessary embodiment of the present invention. As long as they will not deviate from the features of the present invention, all kinds of variations can be available within the range.

For example, in the aforementioned description, although the sliding structure 10 guides the second swaying pivot 8 along a straight line, it can also guide non-linearly. As shown in FIG. 14, the second swaying pivot 8 is guided to an underside in a protruded arc-shape manner. In other words, the sliding structure 10 of the base 2 can be also formed as the underside protruded arc-shape structure. Under this condition; the rising rate (h/q) of the second swaying pivot 8 will be gradually increased following the rearward tilt of the back 3. As a result, referring to the curve B in FIG. 27, the rising of the seat 5 will be gradually enlarged following the increase of the rearward tilt angle of the back 3. Therefore, as shown by the curve B in FIG. 28, the resulted counter force will be gradually enlarged. Even under this condition, when the occupant reclines on the back 3 to tilt the back 3 rearwards, he or she can feel comfortable, thereby increasing comfortableness while being seated. Under this condition, as long as the positions of first, second, third swaying pivots 7, 8, 9, and the shape and curvature of the sliding structure 10 can allow the rising rate (h/q) of the second swaying pivot 8 to be increased gradually when the back support 4 is tilted rearwards, then there will be no special limitation.

Furthermore, in the aforementioned description, if the counter force structure 14 cannot adjust the intensity of the resulted counter force, then it is still acceptable as long as that the intensity of the resulted counter force is adjustable. Referring to FIG. 15 or FIG. 16, on a top of the bottom plate 2 a of the base 2 is provided with adjustment screws 40. By changing amounts of protrusion at front ends of the adjustment screws 40, a pre-stress of the coil spring 15 of the counter force structure 14 is adjusted, and the intensity of the resulted counter force can be adjusted. This way is acceptable. Under this condition, as shown in FIG. 15, on a top of a handle 41 is provided with the adjustment screws 40. Through the handle 41 to turn over and operate, the amounts of protrusion of the adjustment screws 40 can be adjusted without stages, or the intensity of the counter force can be adjusted. On the other hand, as shown in FIG. 16, at a base end of an operating rod 42 is provided with the adjustment screws 40. Through a swaying operation of the operating rod 42, the amounts of protrusion of the adjustment screws 40, or the intensity of the counter force, can be adjusted in, for example, three stages. Besides, on the bottom plate 2 a of the base 2, a bottom plate 43 with screw through-holes 43 a can be fixed by welding or like. The adjustment screws 40 are latched into the screw through-holes 43 a, and are protruded from the through-holes 2 m of the bottom plate 2 a toward the spring plate 16 at the lower side of the counter force structure 14.

Moreover, the locking structure 23 can be also a type which is provided with a spring part in a mechanism and keeps its own functions. Referring to FIGS. 30 to 35, on the support arm 46, and under a condition that the sway of the swaying unit 45 is limited, when the operating structure 44 is operated, an elastic deformation is formed to absorb and accumulate energy that sways and displaces the swaying unit 45. At a same time, once the sway of the swaying unit 45 is possible, an elastic deformation part (or a spring part) 56 can be also designed to develop a function for swaying the swaying unit 45. In this embodiment, the configuration disposed is to bend a middle part of the support arm 46 into the U-shape elastic deformation part 56. Nevertheless, the shape of the elastic deformation part 56 is not only limited to this shape, as described hereafter, as long as that the shape can absorb the displacement energy accumulated to sway the swaying unit 45, and can develop the swaying energy, then there will be no special limitation.

In this embodiment, the turn-over unit 44 of the operating structure is disposed between the left side plate 2 d and the wall plate 2 n of the base 2, and is latched into the axis 48 to prohibit from being turned over. In other words, by inserting the convex part 48 a which is located at the axis 48 into the concaved part 44 d which is located at the through-hole 44 c of the turn-over unit 44, the turn-over unit 44 will be latched into the axis 48 without being turned over. A fixing part 57 is located between the turn-over unit 44 and the bottom plate 2 a of the base 2, and is formed by an elastic material, such as resin, which enables the convex part 57 d between the concaved parts 57 a, 57 b to be pressed down by installing the through-hole 57 c, to latch the convex part 44 e at a bottom of the turn-over unit 44 into the concaved part 57 a or 57 b of the fixing part 57. In this manner, the turn-over unit 44 will be fixed at the initial position, as shown in FIG. 30, or fixed at the locking position, as shown in FIG. 31. By pressing down the concaved part 57 d, the convex part 44 e of the turn-over unit 44 can move between the concaved parts 57 a and 57 b. As a result, the turn-over unit 44 can be turned over between the initial position and the locking position. The fixing part 57 is latched into the concaved part 2 t of the bottom plate 2 a of the base 2.

The arm 44 a is disposed on the top of the turn-over unit 44. The support arm 46 is connected at the place close to the front end of the arm 44 a in a manner that the support arm 46 can sway. The other end of the support arm 46 is connected at the side plate 45 b of the swaying unit 45, in a manner that the support arm 46 can sway.

The axis 48 is inserted into the through-hole 58 on the side plate 2 d of the base 2, and the through-hole 61 on the wall plate 2 n, such that an inner end of the axis 48 can be supported by a wall plate 2 w and the operating rod 20 with the installation tool 21 which can sway, in a manner that the axis 48 can be turned over freely. The axis 48 is provided with a convex part 48 b, and the convex part 48 b is inserted into the concaved part 58 a of the through-hole 58 of the side plate 2 d, so as to allow the axis 48 to be turned over by an angle, and to allow the convex part 48 b to move from a side of the concaved part 58 a to the other side. In other words, the turn-over unit 44 will be restricted from being turned over to the locking position (as shown in FIG. 34) from the initial position. If the base 2 is made by a metal, then it will exceed the range of turning over, allowing the force of reluctantly turning over to be fed into the axis 48, and the through-hole 58 or the concaved part 58 a will still not be expanded, thereby limiting the turning-over angle of the axis 48. As a result, the turn-over unit 44 can be prevented from excessively turning over, the swaying unit 45 can be prevented from excessively swaying, and the installation part at the inner end of the axis 48 can be prevented from being loaded.

As shown in FIG. 35, the inner end of the axis 48 is loaded on a top of a section 59 of the wall plate 2 w. Close to the inner end of the axis 48 is formed with a trench 48 c on which is inserted with a fixing piece 21 a of the installation tool 21 from top. By this way, the inner end of the axis 48 can be supported through the wall plate 2 w and the installation tool 21, in a manner that the axis 48 can sway. Moreover, through inserting the fixing piece 21 a into the trench 48 c, the axis 48 can be prevented from withdrawing. The axis 48 is supported by the operating rod 20 with the installation tool 21, in a manner that the axis 48 can sway, which can reduce an amount of parts, and can reduce an assembly engineering, thereby reducing the manufacturing cost.

The operating handle 60 is fixed at an exterior end of the axis 48. Holding the operating handle 60 and turning it over, can turn over the turn-over unit 44. However, if the operating handle 60 is changed into the operating rod (not shown in the drawings) that is installed at the axis 48, then the turn-over unit 44 can be operated by the operating rod.

In this embodiment, a top of the back support 4 is provided with a convex part 4 i, allowing the swaying unit 45 to be located outside the swaying range under a condition that the back support 4 is not tilted rearwards, and to the swaying unit 45 will be located outside the swaying range, and enter into the swaying range once the back support 4 is tilted rearwards.

Referring to FIG. 30, when the turn-over unit 44 is restored to the initial position, the support arm 46 will guide the swaying unit 45 to the front, and the upper ends of the side plates 45 a, 45 b will be escaped from the concaved parts 4 h of the back support 4. Hence, as shown by an arrow T in FIG. 30, the back support 4 can be tilted rearwards. In other words, the back 3 is not locked.

On the other hand, as shown in FIG. 31, once the turn-over unit 44 is turned over to the locking position, the support arm 46 will sway the swaying unit 45 toward the rear side. As a result, the upper ends of the side plates 45 a, 45 b will be latched into the concaved parts 4 h of the back support 4. Under this condition, when the back support 4 is to be tilted rearwards, the back support 4 will be in touch with the swaying unit 45, thereby prohibiting the back support 4 from being tilted rearwards. In other words, the back 3 is locked.

When the turn-over unit 44 is at the initial position, the swaying unit 45 is pulled back to the front, as shown by the arrow T in FIG. 30, and the back support 4 is tilted rearwards, the convex part 4 i of the back support 4 will enter into the swaying range of the swaying unit 45. Under this condition, after the operating handle 60 is controlled to sway the swaying unit 45 toward the rear side a little, the swaying unit 45 will be in touch with the convex part 4 i, and cannot sway rearwards further. At this condition, the operating handle 60 is controlled to further turn over the swaying unit 45, and the elastic deformation part 56 of the support arm 46 will be deformed elastically, to absorb the accumulated displacement energy that sways the swaying unit 45. As a result, under this condition, once the back support 4, which has been tilted rearwards, is put upright, the convex part 4 i will be escaped from the swaying range of the swaying unit 45, and the swaying unit 45 can sway rearwards. The elastic deformation part 56, which was deformed elastically, will be restored to its original shape, and at a same time, develop its accumulated energy to sway the swaying unit 45 rearwards. Accordingly, under a condition that the back 3 is not able to be locked, the swaying unit 45 cannot still sway even by conducting the locking operation. Therefore, the structures can be prevented from being damaged. Moreover, even that the swaying unit 45 cannot sway, the operation that turns over the turn-over unit 44 can be still conducted, and the swaying unit 45 can sway automatically when it is able to sway. Hence, one can conduct the operation without needing to care whether the back support 4 is tilted rearwards. As a result, the chair can be used more freely.

Moreover, when the back 3 is locked by using the locking structure 23 (as shown by a state in FIG. 31), and once the occupant reclines on the back 3, the swaying unit 45 will sway rearwards immediately. Under a condition that the upper ends of the side plates 45 a, 45 b are latched into the concaved parts 4 h of the back support 4, when the back support 4 is to be tilted rearwards, the support plate 4 c of the back support 4 will be in touch with the swaying unit 45. As a result, the support plate 4 c is changed into a state of pressing the swaying unit 45 which is not able to be pulled back to the front. Under this condition, when the operating handle 60 is controlled to turn over the turn-over unit 44 to the initial position, the elastic deformation part 56 of the support arm 46 will be deformed elastically to absorb the accumulated displacement energy that sways the swaying unit 45. Hence, at this condition, once the occupant stops reclining on the back 3, the support plate 4 c will be escaped from the swaying unit 45, allowing the swaying unit 45 to be pulled back to the front. Accordingly, the elastic deformation part 56, which was deformed elastically, will be restored to its original shape, and develop the accumulated energy to pull back the swaying unit 45 to the front. Therefore, under a condition that the back 3 is not able to be released form the locking state, the swaying unit 45 cannot still sway even by conducting the unlocking operation. As a result, the structures can be prevented from being damaged. In addition, even that the swaying unit 45 cannot sway, the operation to turn over the turn-over unit 44 can be still conducted, and the swaying unit 45 can sway automatically when it can. Accordingly, one can conduct the operation without needing to care whether the back support 4 is tilted rearwards, and the chair can be used more freely.

Furthermore, referring to FIGS. 17 to 19, on a seating accessory of the seat support 6, the seat shell 38 can be also fixed with screws. In other words, on a top of a concaved position 38 a of the seat shell 38 is disposed with the seat support 6, and screws 54 can be used to fix the seat shell 38 and the seat support 6.

Moreover, referring to FIG. 20 and FIG. 21, on the seating accessory of the seat support 6, in addition to that the screws are used to fix the seat shell 38, armrest installation accessories 39 can be also fixed on the seat support 6 by welding or like. In other words, the top of concaved position 38 a of the seat shell 38 is disposed with the seat support 6, and at a same time when the screws 54 are used to fix the seat shell 38 and the seat support 6, the armrest installation accessories 39 can be disposed to install the armrests.

Moreover, referring to FIGS. 22 to 24, on the seating accessory of the seat support 6, the seat installation part 37 can be also fixed by welding or like; whereas, at a same time, a seating plate 55 can be fixed at the seat installation part 37 with screws.

Moreover, referring to FIG. 25 and FIG. 26, the second swaying pivot 8 and the third swaying pivot 9 can be also extended, and the second swaying pivot 8 can be connected with the third swaying pivot 9 by a seat enhancement accessory of the seat support 6. At a same time, a hook 38 b is formed on the seat shell 38, to hook at the first swaying pivot 8 and the third swaying pivot 9, thereby assembling the seat shell 38 at the seat support 6.

The present invention is provided with following advantages:

-   -   1. At the stage that the back starts to be tilted, the operation         that the seat rises significantly and then rises slightly can be         prevented. As a result, the condition that the back is easy to         be tilted by the quick weakening of the counter force after the         back is tilted from a certain extent can be avoided, thereby         improving the comfortableness in using the chair. Besides, by         using the sliding structure to guide the third swaying pivot,         the chair can be constructed simply to reduce the manufacturing         cost.     -   2. The sliding structure guides the second swaying pivot in a         straight line or to be protruded out of the circular arc at the         underside. As a result, at the moment that the back is tilted         rearwards, the rising of the seat will be equalized as shown by         the curve A in FIG. 27, or be enlarged gradually as shown by the         curve B in FIG. 27. As a result, almost the equalized counter         force can be acquired disregarding the rearward tilt angle as         shown by the curve A in FIG. 28. On the other hand, as shown by         the curve B in FIG. 28, when the rearward tilt angle of the back         increases, the counter force can be changed. Therefore, when the         occupant reclines on the back to tilt the back rearwards, a         constant counter force can be maintained, or a proper counter         force can be maintained depending on the angle of the back,         thereby improving the comfortableness while being seated.     -   3. The chair of the present invention is provided with the         elastic deformation part that absorbs the relative displacement         between the operating structure and the swaying unit to         accumulate as energy. As a result, when the sway of the swaying         unit is restricted, the swaying unit will not sway reluctantly,         thereby preventing the structures from being damaged. In         addition, even that the swaying unit cannot sway; the operation         can be still conducted through the operating structure. Under         the condition that the swaying unit cannot sway, the operating         structure is controlled and when the swaying unit can sway, it         will sway automatically. Therefore, the operation of the         operating structure can be conducted without needing to care         whether the back is tilted rearwards, and the chair can be used         more freely.

It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A chair comprising a pintle; a base, which is supported by the pintle; a back support, which is installed on a back; a seat support, which is installed on a seat; a first swaying pivot, which is located on the base, and is connected with the back support in a manner that the back support is tilted rearwards; a second swaying pivot, which is located in front of the first swaying pivot, is at a same level as that of the first swaying pivot, is displaced upwards or above the first swaying pivot, and connects the seat support to the base in a manner that the seat support is tilted upwards and downwards; a third swaying pivot, which is located between the first swaying pivot and the second swaying pivot, is displaced at a level higher than that of a connecting line that connects the first swaying pivot and the second swaying pivot, so as to connect the back support with the seat support to be tilted upwards and downwards, and to be linked with rearward tilt of the back support such that the third swaying pivot raises with the back support; and a sliding structure, which is linked with rising of the third swaying pivot, allowing the second swaying pivot to be guided along a rear upper slant direction.
 2. The chair according to claim 1, wherein the sliding structure guides the second tilting structure in a straight line, or to be protruded out of an arc at an underside.
 3. The chair according to claim 1, wherein the base is provided with a locking structure to fix the back support.
 4. The chair according to claim 2, wherein the base is provided with a locking structure to fix the back support.
 5. The chair according to claim 3, wherein the locking structure is provided with a swaying unit to fix the back support, a support arm to sway the swaying unit, and an operating structure to displace the support arm; on the support arm, and under a condition that sway of the swaying unit is restricted, when the operating structure being operated, and an elastic deformation being formed to absorb a displacement of the sway of the swaying unit for accumulating energy, thereby enabling the swaying unit to sway.
 6. The chair according to claim 4, wherein the locking structure is provided with a swaying unit to fix the back support, a support arm to sway the swaying unit, and an operating structure to displace the support arm; on the support arm, and under a condition that sway of the swaying unit is restricted, when the operating structure being operated, and an elastic deformation being formed to absorb a displacement of the sway of the swaying unit for accumulating energy, thereby enabling the swaying unit to sway. 